Expanding drill



L. P. POND. Expanding-Drill.

No. 225,720. Patented Mar. 23, 1880.

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UNITED STATES PATENT OFFICE.

LEVI F. POND, 0F LUDLOW, MASSACHUSETTS.

ExPANDNG oRL..V

SPEGIFICATION forming part of Letters Patent No. 225,720, dated March 23, 1880.

Application filed October 25. 1879.

To all whom it may concern:

Be it known that I, LEVI F. POND, of Ludlow, county of Hampden, and State of Massachusetts, have invent-ed new and useful Improvements in Expanding Drills, wlich improvements are fully set forth in the annexed specitication and in the accompanying drawngs.

The object of my invention is the construction of an expanding flat drill belonging to that class sometimes called chucking drills; and it consists in forming' a tapering hole in the cutting end of said drill longitudinally and centrally equidistant from each cutting-edge, and fitting to said hole a taperin g plug, which may be driven into said hole to increase the size of the drill by expanding its lower end or to compensate for wear. The sides of said drill are cut away partially over said hole, so that said plug acts as a wedge to spread the partially-separated ends of the drill.

Referring to the drawings, Figure 1 is a side elevation of the lower end of a drill constructed according to my invention. Fig. 2 is aperspect-ive view of the same with the taper plug removed. Fig. 3 is a longitudinal section of a drill, showing the taper plug and a driveplug thercin.

In the drawings, A is the drill. B is a taper plug. d is a drive-out plug. i is a taper hole drilled into one end of a drill. h h are slots cut through the sides of said drill, nearly the length of hole i. bis a transverse drive-out hole through the drill.

Expansive drills as heretofore constructed have been ordinarily too complicated and expensive to admit of their general adoption but my improved drill can be made for very little inore than the cost of an ordinary one, and makes one which can be employed to great advantage for boring holes of slightly-varyin g sizes, and its construction adapts it well for uses which soon wear a drill vtoo small, and call for frequent enlargement by heating and spreading the end, while my drill can be constantly kept np to size within certain limits by driving plug B as the cutting-corners of the drill become worn off.

I construct my drill by making a tapering hole, i, into the drill-bar, leaving a thin Web of metal between the sides of the bar and said hole. l then drill' a hole, b, flatwise through the bar at the end of hole i, and cut a groove or slot, h, on each side of the bar through said Web, separating the cutting end of the bar longitudinally for a short distance up from the end, but not cutting said slots quite np to hole b.

The tapering plug B is fitted to the hole i in the drill, and made long enougl to have its large end project slightly beyond the end of the drill and its small end reach nearly up to hole b.

Between the end of plug B in hole i, I insert a drive-out plug, d, which reaches slightly into hole b.

It is easy to see how my drill is operated. VVhen it is required to expand it to drill a larger hole plug B is driven in until the cutting ends are sufficiently spread apart.

To remove plug B, any ordinary'round instrunent may be driven through hole b and against the end of the drive-plug d.

lt is obviously not essential that plug d be employed for the above-named purpose, as there are many ways by which plug B can be withdrawn from hole i without inserting said plug d behind it.

What I claim as my invention is- 1. An expanding drill consisting of the drill A, having a hole, b, drilled therein and having its cutting end separated into two parts longitudinally and arranged to receive between said parts a tapering plug, B, substantially as and for the purpose set forth.

2. Au expanding drill consisting of the drill A, having its cutting end separated into two parts longitudinally and arranged to receive between said parts a tapering plng, B, substantially as and for the purpose described.

LEVI F. BOND.

Witnesses: v

WM. H. CHAPIN, H. A. OHAPIN. 

